Low oil pressure protection apparatus



Aug. 7, 1962 Filed Feb. 8, 1960 P. E. OLSON I .OW OIL PRESSURE PROTECTION APPARATUS 2 Sheets-Sheet l PAUL E. OLSON 2M im Aug. 7, 1962 P. E. OLSON 3,048,158

LOW OIL PRESSURE PROTECTION APPARATUS Filed Feb. 8, 1960 2 Sheets-Sheet 2 TO ENGINE IGNITION CIRCUIT 28 III 3 i 48 27 4 l 25 v "Ol, "e 30 I m 32 V//I I l IIIIIIIII t II 3| 47 42 I 59 39 I E$533 53 4 58 Eg '3 44 I 4| 34 w I |l A III I OFI- ON 37 57 77 Tl 7| '79 69 d 7a II ao 83' I I 65 8l 62 50 Y/Ilr 56 Illhlmk f/ Hg 4 86 INVENTOR.

PAUL E. OLSON TO I-:GINE

IGNITION CIRCUIT AWHNE/ 3,048 158 LOW OIL PRESSURE PRTECTION APPARATUS Paul E. Olson, Pittsburgh, Pa., assignor to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Filed Feb. 8, 1960, Ser. No. 7,399 8 Claims. (Cl. 12S-196) This inven-tion relates to low oil pressure protection apparatus for machines such as compressors, motors, and the like equipped with an oil lubrication system -and more particularly to such apparatus especially adapted' for use with plunger-type pump pressure systems in which the oil pressure iluctuates.

Various control devices have heretofore been provided to detect low oil pressure in the lubrication system of an engine and to correspondingly control shutdown of the engine. Such control devices7 however, are designed primarily for use with gear-type pump pressure arrangements providing a substantially constant oil pressure in the lubrication system and are not suitable for use with lubrication systems in which the oil pressure iluctuates due to use of plunger or displacement type pumps.

The primary object of this invention is to provide improved apparatus for controlling shutdown of an engine responsively to a below-normal oil pressure condition in the engine lubrication system of the displacement type wherein the oil pressure is subject to fluctuations.

According to this object, one embodiment of the invention comprises a pressure-responsive control valve device subject to the oil pressure in an oil pressure lubrication system of an air compressor, a pressure-actuated fuel control valve controlled by the valve device for causing the fuel control valve to shut oif the fuel supply to a driving engine for the compressor when the oil pressure in the lubrication system reduces to a chosen low value below normal pressure, and a timing device consisting of an accumulator, connected to the valve device, a check valve past which oil under pressure is supplied to the accumulator and a by-p'asswcholce for reverse ow of oil under pressure from the `accumulator on a selected time basis. The accumulator maintains oil pressure on the Valve device, sulicient to maintain the fuel control valve open during the intervals in which the oil pump does not apply pressure to the system, incidental to normal operation of the pump.

I-f the pump fails to `apply pressure to the system for a time longer than the selected time established by the timing device, the back ow of oil through the by-pass choke reduces the oil pressure acting on the valve device to below the chosen low value, thus resulting in operation of the fuel valve to its shut-oit position to cause stoppage of the engine.

Several other generally similar embodiments are disclosed, in several of which the valve device controls a pressure actuated switch for interrupting the ignition circuit of the driving engine if the oil pressure in the `lubrication system reduces to a chosen low pressure.

In the accompanying drawings, FIG. l is a sectional View of the apparatus embodying the invention, shown associated with an engine-compressor unit, including a fuel shut-oit1 valve `device normally supplied with pneumatic pressure and eifective upon release of pneumatic pressure therefrom 'to shut down the engine responsively to an abnormally low oil pressure condition in the oil lubrication system for the compressor;

FIG. 2 is a fragmentary sectional view, showing -a modied arrangement including a pneumatic pressure actuated switch for interrupting the ignition circuit of .the engine and thus stopping the engine responsively to an abnormally 3,043,158 Patented Aug. 7, 1962 low oil pressure condition in the oil lubrication system of the compressor;

FIG. 3 is a View, partly in section and partly in outline, showing apparatus diiiering from that shown in FIG. l, in that certain parts are rearranged in a manner that a fuel shut-off device is actuated to shut off fuel supply to\ the engine responsively to supply of pneumatic pressure l thereto;

FIG. 4 is a fragmentary view of a modication of the apparatus shown in FIG. 3 with -a pneumatic pressure actuated switch device in the ignition circuit for the engine.

Description The embodiment of the invention, shown in FIG. l of the drawings, comprises an accumulator 1, timing means 2, a lcontrol valve device 3 and a shut-off device 4.

For purposes of illustration, the apparatus is shown associated with an engine-compressor unit of the type in- -cludingan engine 5 driving a compressor 6 for supplying compressed air via a pipe 7 to a reservoir 8 provided with a pipe 9 to which any pneumatically driven power device (not sho-wn) may be connected. The engine yand the compressor each have separate and different oil lubrication systems and, for simplicity, the lubrication system for the engine, which is usually of the constant-pressuregear pump type, is not shown, The oil lubrication system for the compressor 6 includes an oil pump 10 of the plunger type driven from the engine camshaft, and Ian oil line or pipe l1 leading, in customary manner, -from the pump l0 to the cylinder bore 12 of the compressor.

The accumulator 1 comprises a casing 13 having a chamber 14 therein in which there is disposed a ball check valve 15 seatable on a valve seat formed at one end of a bore 16 open at its opposite end to oil pressure in pipe 11 via a branch of pipe 11 and a port 17. A piston 18, sealingly reciprocable within a bore 19, is subject et its one side to oil pressure in chamber 14 and opposingly at its opposite side to the force of a spring Z0, one end of which is backed by a perforated screw plug 21 in the outer end of bore 19. The perforations in plug 21 maintain the chamber on this side of the piston vented to atmosphere at all times.

The timing means 2 -comprises a need-le valve 22 sealingly screw-threaded into a bore 22a and adjustable to control reverse flow of oil through an orifice 23 from chamber 14 -to bore 22a and thence via a passage 23a to port 17, in bypass of check valve 1S, lat a selected restricted rate in accordance with the timing desired.

Control valve device 3, hereinafter described in detail, is disclosed and claimed in copending application Serial No. 72,600, led November 30, 1960, by Charles Doolittle and Arthur J. Bent, and assigned to the same assignee.

Control valve device 3 comprises a casing 24 having a transverse slot 2S in which a lever 26 is fulcrumed, intermediate its ends, on a pin 27 for rockable movement. Lever 26 has suitably attached thereto a handle 28 for manual rocking Iof the lever, said handle extending upwardly through an opening 29 or slot in a casing cover 30, suitably secured to casing 24, as by screws.

A pair of pistons 31 and 32 are sealingly reciprocable in respective spaced parallel bores 33 and 34 in the casing 24 in such a manner as to contact corresponding opposite ends of `lever 26. Piston 31 is subject to oil pressure supplied to ya chamber 35, formed in bore 33, from chamber 14 of accumulator 1 via a passage 36 in casing 13 of the accumulator, a port 37 of casing 24 and a passage 38. Port 37 is threaded at its outer end to receive a threaded boss of casing 13 to effect joinder of the casings 13 and 2.4. Piston 32 is subject to the force of a spring 39 coaxially disposed in a chamber 40 formed in bore '34. Spring 39 exerts a force corresponding to a selected low oil press-ure substantially lower than the normal oil preschamber o6 wbiehs always-opendoen engineueltinlet port 'via `a pipe `6K7.' `When chamber 54 of device" .1i-f l u f i vented, valve 63 isbiasedf by, spring* 61 intofengagefrnent with -a valve seat 68 formeda-t `oneendrof aportthrough... t

sure required in the lubrication system of the cpzompressor1l e i 1 to maintainproper lubrication of the components therein.` Pistons 31 and 32 act opposinglyto rocklever 26 iny either a clockwise or a icountercloclrwise direction according to whether the force of the oil pressurein chamber 35 'z acting on piston 31 isy greater or less than the force of spring 39 acting against piston 32, respectively. f

The foregoing structure including the,y pistons 31 and 32 and the `lever '26 are hereinafter sometimes referred to as the `actuator means.

inner end of a bore 42 in casing 2d and is `bias-ed by the force of a coaxial spring 43, interposed between valved 'y femelles of device 3, to `the reservoir f8; when alhandle of valve 1 6.9 is moved tothe fcn 'positionfto control the-shutdown of the engine-compressor from a remote location. e

A valve 41 of the disc or poppet type is disposed in the and an end wall ofbore d2, toward and against an annular t valve seat 44 formed on a valve` seat member 45 in the form of a piston sealingly disposed in the Outer end of bore 42. A plated@ suitably secured "to thefcasing wall,

-as by a screw, serves to retain the membery 45k `ifi/the bore 42. Member 4S has a centralbore 47 therethrough of y or free end extends slidably throughan aligned aperture' s in plate 46 into bore 47 of seat rnen'iher 45 in sealed'con` tact therewith. Stern 48 is shifted downwardly by clockiwise rocking movement of lever 2.6' to causethe freeend of stem i8 to engage and to unseatvalvedl fromfse'at 44 against the force of spring 43 and the pressure of fluid acting :on valve 4l in a chamber 49 open to reservoir 3 p njopera'tionplet y paretus of FIG.r l is conditioned with .ther vhandle of kOperation f y it beassumed initially that the apofhon valve y69 in off position, in which it is shown,

for venting 'chamberr 40, that the needle valve '22 is adjusted to permit la desired nate of return ofk oil under Y `inessure'kffrom chamberl4 tojport'l, and that the engineycompressor unit is shutV down.

components of they apparatus will be in their respective vpositionsy showny in the drawing. Chamber will be devoid ofioil under pressure yandlever 26 will be biased to its Acouriterclockwise limit position or engine cut-oirr position in which, handle 2B is adjacent the left-hand end of t slot 29 in cover 30 andin which the left-handend ot 'lever Zocontactsthe casing 24at the bottom of 'slot 2.5; "as viewed inthe drawing, andk stem 45s will be in itsy up- .l

ward limit position defined by the lip onthe free endet stemSbeng/in spaced relation with valve vi1 .to permit via a passage 50 and a pipe 51. `Cornmunication is estabi lished past valve di, while thus unseated, viarwhich'liuid under pressure iiows from chamber p49 .to an yannular recessorchamber 52, formed in the outer surface of valve j seat member 45 via bore 47 and a plurality .oftran'sverse ports 53 inseat member n45, Aand thencey to a chamber 54 within a casing 5S of `shut-'off device '4 viaa passage anda pipe 57; Counterclockwise rocking movement of f lever 26 moves stem 48 upwardly to a poSiOu, in which it is shown, wherein thefree end ofstemd is raised` out of ycontact with valve 41` and wherein valve 41' is ,biased ,i

into engagement with seat 44 by spring d3.;r In the latter position of stem `48,..iiow of lluid underpressure from via the bore in stem '48.

A cylindrical plug S8 issealingly dispos-ed` a bore 59 y i corresponding in dimensions tobore 42 vand open to the same passages 5l) and 56. Bore 59 is provided to permity i interchange with plug, 5810i? valve seatr member 45, yvalve d1 and spring 43 when itis desired to use `a'modiiied form'y of shut-o device` as will be explained slater. Plate` 4'5 also serves to holdV plug 58 within bore S9. f

` The shuto-device 4 `comprises a diaphragm. (geuitL ablyclamped between sections `of casingwSSiand subject :at

y its one side to the pressure of iiuid inchamber 5,4 and opposingly to the force of a coaxial spring `61 disposed in an atmospheric chamber at itsother side. p, YAfollower associated with diaphragmi) has ka valve stem 62-extendfl ing therefrom and stem 62 has a poppet valve 63 formed atits end. Valve controls the ,supplyiof fuel from a` A chamber `ed, open via a port iii/casing tolanengineffuel supply line 65k connected to. a `fuel@ pfnotshoxvnkf t Remote enginey cnt-out control is! provided by oi-n l y onr valve 69, interposed'in fa/branchoff pipe 551, fon conff necting chamber 40 of devicerviaia passage 791ifc'asiug;

'isflreptroclredmits'cockwiseliniit position.- L" yltyyz llbequnderstooti; thatthetoree Aci springgi `ronf"` pistonf me accumulator 1 continuesito'ei'rert normal i.

venting otchambe'rdof deviced via stern 43.k f

To start the engine, it is first necessary to move handle '2S ofr levergZtSL to its` clockwise limit' positionor engine f 4running. positionadjacent the right end of'slot 2K9 of cover 30, in cpnsequence of ywhich lever 26 is correspond/ ,ingly rocked `clockwise to itslimit position in which the right-*hand end of-lever 26 contacts casing 2.4! vat the botf torn oslotpZS, as viewedin the drawing, against. the

. forcefof spring l39 `of device ySi. Valve ystem d8 is thus i movedtdownwardlysuccessively from its uppermost position intoV engagement withvalve 41 and thenkfurther downwardly ,to unseat valve 41 from seat 44 against theforce yofspringdfairl ythe/pressure yof' fluid Aacting on valve il With valveunseated, from seat 63 communication is Wesillbillsi'led. lthl'llgh` may kfkfon` y y `ddfto ychamber ,66 and` thence-to pipe 67 and torthe engine. Whi'le holding the handle 2S in itsclockwise' limit fposition, thegeng-ine Sean thusbe started by` the usual chamber 49 ofy device 3` lto chamberfdof device` 4 is cutv ,f ofir and chamber 5d of ydevice 4 is ,vented `to yatmosphere engine,startingfprocedure.

IAs soon yas ,th engine on valve 41, 'so as `to keep the lever .26 rocked in its` t clockwise/limit, positionrwithout the aidof manual force'` .e i p i ofthe handles`r ltfwill thus betapparent thatthe engin `unasilnrrgl asaznorrnal `oilJpressune' is f1 Wl. i maintained in lubrication '1 system. and s the lever pressure ontheoil'in chamber 14 andk thus the `oil pres# surey in chamber' 3S continues to exert sutcient force to rhold lever-26fin its clockwise' limit position Anctwithl` standing momentary' pressure rareaotionsin the lubri-L cation 'syst ernlfduring the: intake stroke `ofthe e liee In this case all ofthey y 5` starts, `pump `10 rforces oil .lunderlpressure into thelubrication system andr into portw f 17 of device 1, via pipe 11,` thence past 'check valve 15 into chamber` y14'y of the accumulator. y

`charnlmerld actsagainst piston 18 to compress spring .i

. @an amount .corres'pcndixflg` to theloil pressure establishedr Y invncharnber 14; Oilunder pressure` from chamber 1.4.#

f ftiows, `tocharnber35 of devicefS via. passage, port '37r A ,s

andfpassageotvdevice 3 andacts against pistonil `3S acting onlpiston 31 increasesto'a valuehigher thanff kthe cumulative `forces of spring 139 acting on piston 32.;

6.0i of spring dyacting on valve 41,y and theforce corre- Y Oil pressure in deplace that the restricted backiiow of oil under pressure via orifice '23 from chamber 14 to pipe 11, while the pressure rarefaction occurs, is not of suiiicient volume to etect a reduction of the mean 4oil pressure acting on piston 35 to permit reverse tilting of the lever 26 in a counterclockwise direction.

As a matter of fact, the orifice 23 so restricts backow of oil under pressure that a selected number of seconds, such as thirty, must elapse before the oil pressure in chamber `14 and thus in chamber 35 reduces sufficiently to allow reverse tilting of lever 26. Thus as long as the pump continues to operate properly, the momentary pressure rarefaction in the lubrication system incidental to the intake stroke of the pump piston does not affect the position of the lever 26.

However, if for some reason the pump 10` ceases to operate to maintain normal oil pressure in the lubrication system, the oil pressure in chamber 14 and thus in chamber 35will be reduced after a given interval of time, such as thirty seconds, due 'to backiiow of oil through the orifice 23 to the pipe 11. In such case, when the oil pressure in chamber 35 decreases to a value below that corresponding to the 4force of spring 39, lever 26 will be rocked to its counterclockwise limit position, as previously defined, carrying stem 48 out of engagement with valve 41 and allowing valve 41 to seat on valve seat 44. Chamber 54 of device 4 will thus be vented via pipe 57, passage 56, bore 47 and stem 48. When chamber S4 is vented, spring 61 of device 4 will bias the diaphragm 60 `to its upper limit position dened by a stop 71 in the casing 55 wall. Va-lve 63 of device 4 will be correspondingly carried upward into seating engagement with valve seat 68 and will be effective to cut ofr the flow of fuel to the engine and consequently cause the enginecompressor to shut down.

lf desired, the engine may be cut out from a remote location by moving the handle of the olf-on valve 69 to its onf position, as previously described. In this event, uid under pressure will flow from the reservoir 8 past valve 69 to chamber 40` of device 3, and will act on the inner face of piston 32 to cause the piston, in conjunction with the force applied by spring 39` in bore 34, to exert a force on lever 26 which, assuming the engine is running, is positioned in its engine running or clockwise limit position. The unit iiuid pressure supplied to chamber 4t) is of a value higher than the value of the normal oil pressure in the lubrication system and consequently a counterclockwise moment is exerted on lever 26 which then transmits a back pressure to the oil in chambers 35 and 14 via piston 31. Check valve 15 thus seats and oil under pressure trapped in chamber *14 escapes therefrom at a restricted rate past the needle valve 22. The combined force of the pressure of fluid under pressure in chamber 40 and of spring 39 exerted on lever 26 will act to push piston 31 down into bore 33 displacing oil from chamber 35 into chamber 14 of the accumulator 1 to shift piston 18 in the accumulator upward against the force of spring 20. While the lever 26 is rocked counterclockwise to its limit position, the stem 43 will be shifted upward, valve 41 will be seated and chamber 54- of shut-o device 4 will be vented via stem 48 in the manner described, cutting out operation of the engine. It will be noted that the value of spring is such that when chamber 14 is charged with oil at a normal pressure, spring 26 will not be fully compressed by piston 18.

FIGS. 2, 3 and 4 show modified embodiments of the apparatus. The same numerals used in FIG. 1 to identify the various components of the apparatus will hereafter be used to identify like components.

ln Fl'G. 2, a modied shut-oit device 72, shown as a pneumatic control switch, is provided in the ignition circuit oi the engine for controlling shutdown of the engine 5 upon abnormally low oil pressure in the lubrication system of the compressor 6. Device 72 comprises a piston 73 sealingly reciprocable within a bore in a casing and subject at one side to pressure of fluid in a gni chamber 74 open to pipe 57 and at its opposite side opposingly to the force of a spring 75 disposed in an atmospheric chamber. A stem on piston 73 has an insulated contact member 76 for engaging a pair of stationary contact members to close the ignition circuit of the engine.

In the operation of the apparatus ot FIG. 2, when oil pressure in the lubrication system of the engine is normal and correspondingly lever 26 is rocked to its clockwise limit position, pipe 57 will be charged as previously explained, and pressure of uid from pipe 57 will flow to the pneumatic switch 72 to move piston 73 downwardly against the force of spring 75 thus causing Contact member 76 to close the engine ignition circuit t0 permit operv ation of the engine. When the oil pressure in the lubrication system reduces abnormally, pipe 57 will be vented as previously described and spring 75 will bias piston 73 upwardly to thereby carry contact member 76 upwardly thereby to open the ignition circuit of the engine for electing shutdown of the engine.

In FIG. 3, another modified shut-oft device 77 is shown connected to valve device 3. Device 77 comprises a casing having therein a movable abutment, such as a diaphragm 78, subject at one side thereof fto pressure of fluid in a chamber 79 open to pipe 57 and opposingly to the force of a spring S0 in an atmospheric chamber at its opposite side. A stem, having 4a valve S1 at one end, is operatively connected to the diaphragm '7S 4at its opposite end, said valve 81 being unseatable from a valve seat 82 to control supply of fuel from a chamber 83, open to la fuel ,tank (not shown) via pipe` 65, to the engine via pipe 67.

Device 77 is operable in a reverse manner from device 4 shown in FIG. 1 in that when chamber 79, which corresponds to chamber 54 of device 4, is pressurized, valve 81 cuits oft the flow of fuel to the engine whereas, as already explained, when chamber 54 of device 4 was charged with fluid under pressure, vfuel was supplied to the engine.

p In `order to adjust valve device 3 to charge chamber 79 of device 77 with fluid under pressure instead of venting it so as to effect shutdown of the engine 5 when the oil pressure in the lubrication system of the compressor 6 decreases yto an abnormal pressure, it is only necessary to interchange valve member 45, valve 41 and spring 43 with plug 58 and to pivotally connect stem 43 to :lever 26 intermediate piston 31 and pin 27, as shown in FlG. 3.

With these components rearranged the operation of device 3 `is the same as that `described for FIG. l with this exception, that when lever 26 is rocked to its counterclockwise llimit position as when the oil pressure yin the lubrication system is abnormally 210W, stem 4S will be in its downward limit position thereby unseating valve 41. Chamber 79 of device 77 will thus be charged and the pressure of flu-id therein will cause diaphragm 7% and valve 71 of device 77 to move downwardly for seating valve 81 on seat 82 .thus cutting oil flow of fuel to the engine; and when lever Z6 is rocked to its clockwise limit position, as when the oil pressure in the lubrication system is normal, then lever 26 will carry stern 4S upward out of `engagement with valve 41, whereby valve 41 will cut olf the flow `of fluid to chamber '79 and the latter chamber will be vented via :stem 48 to cause valve S1 to be unseated for opening the fuel supply line to the engine.

FIG. 4 shows a modified shut-off device S4, such as a pneumatic control switch, substituted for device 77 of FlG. 3. Device 84 comprises a piston 85 sealingly reciprocable within a bore in a casing and subject at one side to pressure of fluid in a chamber 86 open to pipe 57 and at its opposite side opposingly to the force of a spring S7 disposed in an atmospheric chamber. A stem on piston 85 has an insulated contact member 88 for engaging a pair of stationary Contact members when the piston is biased to an upper position byispring S7.'

With this ari-i.

acte, les g f rangement of the apparatus, in operation, chamber 86st device 84' will be charged when the pressure-inthe lubri-U cationfs'ystem of the engine'isabnormallylowand"lever` ,26 is correspondingly rocked to -its counterclockwise pof sition as previously explained, and the ypressure of fluid `acting on piston 85 will move the ypiston `and contact memkber 53, operatively connected lthereto, downwardly'to diss engage the 'contact member 8S from the stationary con'- tact members in the ignition circuit for opening ,the circuit and thereby shutting down the engine; when'charnber f f ported, and characteiizedtin that said control ,valve means f `,chosen low value only after the expiration of a certain selected lengthjof time.

4.y Low-oil pressure protection apparatus, as `claimed in 'i clainrl,r further including` casing means by kwhich said' control valve means land said actuator means are. 'supis selectably 'locatable in either one of a pair oi' spacedy bores `in saidcasingimeans, according to whether pressure y of the'engine..

86 is vented in the manner' described for FIG. thenv f r` spring' 87 of device 84 will bias piston 3S land contact member 88 upwardly tocause member 3S to engage the stationary contact members for closing the engine ignition circuit to permit operation of the engine.

lt will be noted that, if 'thetiming feature is 4`not desired, the apparatus'may be operated without the accumu-` lator and the timing means, as by connecting pipe ,11 directly to port 57 of device 3, provided `a constant pressure type of pump is employed for the lubrication sys-tem. In f y this case, oil under pressure from pipe ll will be eftec'tive in chamber of device 3, when` the `engine is operating,

of fluid to be supplied to or exhausted fromsaid shutoi'means by saidy :control valve means to eiect shutdown `5. Lowl oil pressure protection apparatus as claimed ,in r`claim 1,r further includingA and characterized by casing means on which said control valve means and saidactuator means are supported and in which there arcy a pair of yspaced bores of identical diameter, and a sealing plug' dis-;

posed Vinione ,loftsaid bores, said valvey 'means beingdisyposed ini the `otherrd said bores` andoperatively connected to said actuator means, said bores being of identical diameter so that said valve meansand sealing plug are interchangeable therein according to whe-ther pressure of Quid is to be supplied to or exhausted from said shut-oitV to rock lever 2.6 clockwise toits fuel line opening positiony t f or ignition circuit closing position. Upon areduction or oil pressure in the oil lubrication system from thes'higher normalpressure to below a value corresponding fsubstang tially to the value olf-spring 39,.,lever 2d willH be rocked f counterclockwisev by spring 39 tofshut oft the engine.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. Low oil pressure/protection apparatus for anoiln lub;-

rication system of engine-driven m-achinewhen the oil f pressurein Ithe system decreases from a normal pressure to below a chosen low value, said `apparatus comprising a source of fluid under pressure, a iluid pressure controlled shut-oft means yfor effecting stopping of the engine, valve means for controlling the supply of liuid under pressure from said source to andlrelease of fluid under pressure from said shut-otr" means, `actuating means tor said valve means including means operatively connected to and communicating with said lubrication system so as to be re- `V sponsive to a torce corresponding to said oil pressure ink said lubrication system Iand means for applying opposingly tosaid oil pressure force a biasing force corresponding to the said predetermined chosen ylow value of oil pressure, said `oil pressure responsive means 'and said predetermined biasing forcey means being operative to actuate said valve means for controlling the supply offuid under pressure to and release vof iluid under pressure from` said shut-ott means so as to eiect stopping of said engine when said oil pressure in said lubrication system decreases from said normal pressure to below said chosen low value, and timing means lbetween said lubrication system and said actuating means for delaying tor a selected interval of time the actuation of said valve. means when said oil pressure in said system decreases below said chosen low value of oil pressure.

2. Low oil pressure `protection apparatus, as claimed in claim 1, in which said timing means comprises means ,n for preventing reduction of the oil pressure acting on said actuator means except tat a selected restricted rate, thereby to delay operation of the said control valve means to eiect operation of the shut-off means to stop the engine f for a selected interval of time after reduction of oil pres'- sure in the lubrication system is initiated.

3. Low oil pressure protection apparatus, ask claimed in claim l, in which said timing means comprises a check Valve past which oil under presusre is supplied to said actuator means,kk a pressure accumulator -forsmaintaining oil pressure on said actuator means during rarefjaotions f of pressure inthe lubrication system, :and `a restricted oriiice via which loil under pressure Hows back to the lubrication system at `a rate such that the oil pressure on said actuator reduces from said normal pressure to` below said means by said'eontrol valve means to eiect shutdown of y y 6.k A ylowoil pressure protection apparatus `for use with f aupoil lubrication system oan engine-driven machine, 4'

said apparatus comprising a source ot fluid under pressure,

V"tiuid pressure actuated;shut-.off` means operative in a nor.- mal position'permitting operation `ot the engine upon' supply of iiuid under pressure thereto and operative at `a shuto `positionr to eiect stopping of the engine upon venting f l ,of fluid underwpressure therefrom, arvyalve means having a` supply position" `for supplying huidr under pressure to said shut-off means and an exhaust position for venting fluid under pressure from said shut-off' means, actuator means for rsaid valvey means including means operatlvely connected to and communicating with ysaid lubrication system so as to be responsive to a force corresponding to the oil pressure therein 'and means-for applying opposingly to said oilpressure -force a biasing force corresponding to a chosen low value below a cert-ain normal oil pressure,.said

oil ypressure responsive means and said biasing force means being 4operative to movesaid actuating means for actuating said valve meansto said supply position when the oi-l pressure in the lubrication system increases above said chosen low value of oil pressure land for actuating said Valve means to said exhaust position when the yoil pressurek in said lubrication system decreases from said `'norm/al position below said chosen low value kof oil pressure, .and timing .means between said lubrication systeml and said actuating means for delaying fora selected interl in a normal position permitting `operation of the engine f upon venting of fluid under pressure therefrom uudoperative to la shut-oir position to effect stopping of the engine upon supply of liuid pressure thereto, a valve means having a supply position for supplying fluid under pressure to said shut-off means and au exhaust position for venting huid/'under fpressurefrom said shut-oit` means, actuating means for actuating `said valve means to one of said positions including `means Yoperatively connected to yandicornmunicatiug with said lubrication system so as to be responsive to a force corresponding to the-oil pressure `therein and means for applying a biasing force corresponding to a chosen low value below a cert-ain normal oil pressure/arranged opposingly to said yoil pressure'responsive means, said oil pressure responsive means and said biasing force means being operative to actuate said valve means to its supply position when'the oil pressure in the lubrication system decreases below said chosen low value of oil pressure and to actuate said valve means to its eX- haust position when the oil pressure in the lubrication system increases `above said chosen low value of oil pressure, and timing means between said lubrication system and said actuating means for delaying for a selected interval of ltime the actuation of said valve means when said oil pressure decreases below said chosen low value of oil pressure.

8. Low oil pressure protection `apparatus for an oil lubrication system of an engine driven machine, said apparatus comprising la source of pneumatic pressure, a pneumatic pressure controlled shut-oit means for effecting stopping of the engine upon decrease of oil pressure from a normal pressure to below a chosen low value, `a control Valve device `comprising a casing, valve means in said casing for controlling the supply of pneumatic pressure to and release of pneumatic pressure from said shut-ott means, actuating means for said valve means, said actuating means comprising a valve actuating lever, a fulcrurn pivotally mounting said lever intermediate its ends on said casing, and a pair of pistons each reeiproeaole in respective spaced bores in said casing means and ecntacting said lever at points on opposite sides of said fulcrum, one of said pistons being subject to the pressure of oil in the lubrication system and the other of said pistons being subject to a predetermined bias force thereby subjeoting said lever to opposing moment forces for rocking said lever 4on said fulerum to different positions thereby to actuate said valve means for supplying pneumatic pressure to and for releasing pneumatic pressure from said shut-oilc means so as to effect stopping of the engine when the oil pressure in said system falls below said chosen low value of oil pressure.

References Cited in the le of this patent UNITED STATES PATENTS 899,263 Richards Sept. 22, 1968 1,896,459 Mullin Feb. 7, 1933 2,112,664 Dube Mar. 29, 1938 2,497,695 Sheppard Feb. 14, 1950 2,768,708 Cooper Oct. 30, 1956 

